Most backend engineers implement multi-tenant quota checks using a standard "read-then-write" pattern. In production, this pattern is highly unsafe: SELECT grading_scans_remaining FROM profiles; If greater than 0, execute the application logic. UPDATE profiles SET grading_scans_remaining = grad...
Source: [Dev.to](https://dev.to/dollykm49/defeating-the-multi-tenant-saas-concurrency-trap-in-postgresql-5c9k)